NERVOUS SYSTExM AXD SUPRAKENAL BODIES IN THE SPAUllOW. 741 



3G. Observations on the Development o£ the Sympathetic 

 Nervous System and Suprarenal Bodies in the 

 Sparrow. By A. StJBBA Rau, B.A., M.Sc, F.R.M.S., 

 Derby Scholar, Department o£ Zoology and Compara- 

 tive Anatomy, University College, and P. H, John- 

 son, B.A., B.Sc, F.Z.S., F.R.M.S., Demonstrator in 

 Zoology, Department oi' Zoology and Comparative 

 Anatomy, University College, London.* 



LReoeived May 29, 1923 : Read OctoW 23, 1923.] 



(Text-figures 1-20.) 



Introductory. 



In the course of an investigation suggested to us by Prof. 

 J. P. Hill, as to the origin and development of the suprarenal 

 bodies in the Sparrow, we have been led from a consideration of 

 the source of the chromaffin cells in those hodies, to an exami- 

 nation of the development of the sympathetic nervous system. 

 The origin of this system has been a much-debated question for 

 many years, and the excellence of the material provided for us 

 by Prof. Hill has tempted us to put forward an account of our 

 observations on this subject, more particularly as concerns the 

 relations of the so-called primaxy and secondary sympathetic 

 cords. 



While confirming on the whole the view maintained by the 

 majority of modern embryologists as to the ectodermal origin of 

 the sympathetic system, the investigation has brought to light 

 certain interesting facts which do not appear to have been 

 recorded by pi-evious observers, while we venture to think that 

 the confirmation of previously recorded observations may be of 

 some value. 



Our observations liave been made on a series of nearly a 

 hundred Sparrow embryos collected during the years 1919-21. 

 Unfortunately little is known as to the exact age of these 

 embryos, but by a careful comparison of the stages of developr 

 ment reached we have been able to ai^range them in a series. 

 Keibel's ' Normal Table of Chick Embryos ' has been of con- 

 siderable assistance in this task. 



The embryos were fixed by various methods, the most successful 

 being that of Gerhardt. Pi'of. Hill also placed at our disposal 

 some chick embryos treated by Bielschowskj^'s method. The 

 best staining results were obtained by the use of Heidenhain's 

 iron hsematoxylin. 



* Commuiiiciited by Prof. D. M. S. Watson, F.R.S., F.Z.S. 

 Proc. Zool. Soc— 1923, No. XLTX. 49 



